It is possible to measure the third nonlinear susceptibility in the continue laser Z scan set up and why if it is not ?
Generally, pulses are needed to investigate third order susceptibility in matter. When using CW laser, photothermal effects dominate. Mathematically speaking, changes in the refraction index due to gradients of temperature can be considered a third order effect. However, most of the authors consider it a K1 x K1 effect, since the signal is proportional to the first order of the intensity. If there is any other third order effect it will be probably be masked by the photothermal effects.
In conclusion, we should not deny that third order susceptibility effects can be detected using CW laser, the point is that they will be very difficult to see because of the presence of photo thermal effects.
Thank you very much , dear Dr. Professor, Aristides Marcano Olaizola for the snswer.
Ragards
Raad
With using Cw laser in Z scan technique will produce thermal effective on the other hand with pulsing the electrons transition will be occurring.
Therefore, the third nonlinear susceptibility is only can be measured with the pulses.
thank
Raad
It is possible to calculate
Real part or imaginary part of this the third order factor?
Yes, we can because the third-order susceptibility composed from two-components: the real part which it depends on the third-order@@@@ refractive index which calculated from the parameters of closed aperture z-scan, and imaginary part which deepened on the absorption coefficient that measured from the parameters of open aperture z-scan whatever the kind of laser used pulsed laser or CW laser.
Amal Jaffar, thank for this kind reply
Yes you are write by sumation the real and immaganiary parts,
but in the case of the electron transions not by the optothermal effect.
According to the second snd more terms of mean equation between the Polrization and the electric field of the optical waves.
Regard
Raad
In the electronic transtions, there is general equation fir polarization related with the electric field and the susceptibility, there for in this case , can by the changing in the nonindex refraction &nanabsorption coefficients calculate this suscebtibility.
But in the photothermally which is obtainable by using CW lasers dont related with the main equation between E & P and susceptibility
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